Clamp contact devices are known from EP-A-0 218 133, FR-A-2 524 721, and DE-B-11 96 741. In all these spring clamps, which are built and operate according to the same principle, clamp contacting adequate for the stated purposes is achieved. However, these clamp devices do not provide for an electrical connection with a plug-in contact element.
DE 28 00 307 A1 discloses a contact point with a movable spring leg which rests on a printed circuit board and which runs at an angle thereto and a fork spring located on the outside of the deflectable spring leg. This contact point is suitable for electrical connection to a plug pin, but not for clamp contacting of a cable. But primarily this component has very large dimensions which make it essentially useless for many applications due to the spring leg which rests on the board and which is pulled forward in the plug-in direction, and especially due to the fork spring provided on the outside of the movable spring leg.
Furthermore, DE 42 33 446 C1 discloses a clamp contact device as is shown schematically in FIGS. 5 and 6, FIG. 5 showing the clamp contact means in the closed, or clamped, state, and FIG. 6 shows the clamp contact device in the open state, in which the cable can be inserted in the clamp contact device. In this known clamp contact device in plastic housing 1 there is clamp contact spring 2 which is riveted or caulked to support body 3 likewise located in plastic housing 1. Clamp contact spring 2 has fixed spring leg 4 and deflectable spring leg 5, and the latter can be pressed inward towards fixed spring leg 4 by means of lever 6 against spring force (compare FIG. 6). A cable (which is not shown), or the stripped conductor of a cable, can be pushed through opening 7 in plastic housing 1 into the latter and between deflectable spring leg 5 and stop 8 of support body 3. When lever 6 is released the inserted cable or inserted cable conductor is pressed against stop 8 by the spring force of deflectable spring leg 5 and in this way electrical contact is established between the cable and clamp contact means or support body 3. At the same time deflectable spring leg 5 mechanically fixes the cable or cable conductor, one free edge 9 of deflectable spring leg 5 acting as the contact blade.
This clamp contact means is complex, both with respect to production and also mounting. To achieve sufficient spring action contact spring 2 must be produced from spring steel so that additional support body 3 of bronze or brass is necessary to ensure adequate contacting and low electrical resistance. To deflect spring leg 5, i.e. to open or close the clamp contact device, additional lever 6 is necessary. To open the clamp contact device a tool is necessary, for example a screwdriver, which increases the operating effort of the user. In addition, the clamp must be mounted securely on a circuit board or a housing since for actuating the clamp both hands are necessary, one for holding the cable and the other for holding the tool, so that the hands are no longer free to hold the clamp itself. Another important disadvantage of this known clamp contact device is that it can be miniaturized only with high cost.